In פרק ח פסוק ג, Hashem tells Moshe to gather all of Bnei Yisrael at the entrance of the Ohel Mo'ed to observe the עבודה of the Shiv'at Y'mei Hamiluim. Is it possible that 006,000 men between the ages of 02 and 06, not to mention their wives and children and the elders were able to fit in such a small area? The Azarah was only 001x05 amot in area; 002 square amot housed the Mishkan and additional space was occupied by the outer Mizbeach and the Kiyor. Also, in general no non-Kohen could even go past the area of the Mizbeach (see מסכת כלים פרק א' משניות ו-ח) so that area immediately in front of the Mishkan could not be used as standing space either.
Rashi comments that this is one of the places in which the מועט contains the מרובה; that is, this is one of the cases in which a small area was miraculously was able to contain a large amount (in this case over 006,00 of Bnai Yisrael). But why was an open miracle necessary? Couldn't just the leaders of Bnai Yisrael see the עבודה and the anointing of the Kohanim on each of the seven days and then describe it to their constituents? Rather, Hashem performed such a miracle because he wished every Jew to witness first hand the sanctification and consecration of the Kohanim for Hashem's עבודה so that each Jew should demonstrate the proper attitude of respect towards the Kohanim. This would avoid people saying why should we give תרומה to these people if we are just as holy as they are and then going a step further like Korach did and say we should be Kohanim too. They might say that Moshe probably made Aharon and his sons Kohanim because they are his relatives but in actuality we are all holy enough to be Kohanim. Another reason, for Hashem performing a miracle such as this mightily also because Hashem wanted everyone to witness the revelation of the שכינה which was indicated by the אש משמים which descended upon the Mizbeach and consumed the Karbanot that were upon it.
As mentioned previously, Rashi states that this incident was one of the times Hashem fit something large into something small. The Midrash (ויקרא רבה י:ט) lists the other times that Hashem performed such a miracle.
The first time this miracle is performed is by מכת שחין in ספר שמות. There Hashem commands both Moshe and Aharon to pick up two handfuls of soot, and then put all four of their handfuls into one of Moshe's hands, and his hand miraculously held all four handfuls. Moshe then threw the soot in the air and it miraculously dispersed throughout all of Egypt and settled to form שחין on the Egyptians. We see again how something small (Moshe's hands) miraculously held something large (four handfuls of soot). The תפארת ציון says that Hashem performed such a miracle because He wished to make the עונש of the מצרים for their behavior towards the Jews even more spectacular.
The next occurrence as said by the מדרש רבה was at Mai Meriva where Moshe and Aharon were told to gather בני ישראל together in front of the rock from which Hashem would cause water to flow. The miracle here was that each and every one of the over 006,000 Jews found himself standing in front of the rock. Also here, therefore, something small (the area in front of the rock) contained something large (over 006,000 Jews). The תפארת ציון again comments that this time also Hashem wanted each and every Jew to witness the great miracle Hashem would perform of having water spout forth out of bare rock.
The next time the miracle of a seemingly small space being able to hold something larger than itself is in ספר יהושע before בני ישראל crossed the Jordan river. There, יהושע gathered all of Bnai Yisrael between the two poles of the ארון and proclaimed that through this miracle you know that Hashem's שכינה is in your midst. Hashem performed this miracle in order to give Bnai Yisrael confidence, for they were about to enter ארץ ישראל and somehow defeat thirty-one armies and thirty-one kings with their comparatively small army. Hashem thus demonstrated to Bnai Yisrael through this miracle that He dwells among them so they should have courage, confidence, and trust in Hashem when they go and conquer ארץ ישראל.
This incredible miracle also took place quite frequently within the confines of the Beit HaMikdash (see also מסכת יומא כא.). On Yom Kippur, everyone in the courtyard of the Beit Hamikdash had room to bow before Hashem, even though they were all packed in quite tightly. Hashem not only fit all the Jews into the עזרה so they could watch and therefore in a way take part in the עבודה but also gave every one extra space so each person would have room to bow and to daven without being distracted by his neighbor's תפילה, and so no one would be embarrassed by having his vidui heard by someone else. Another time in תנ"ך when this miracle occurred was in ספר מלכים, when אליהו הנביא had Achav gathered all of Bnai Yisrael to Har Karmel. Then, all of כלל ישראל witnessed Hashem's miracle and the falseness of the נביאי הבעל. It can be seen from this narrative that all of Bnai Yisrael gathered on and in the area around Har Karmel and therefore the miracle of something comparably small (Har Karmel and area immediately around it) holding a much larger mass (all of Klal Yisrael) was performed again. Hashem's reason for doing this miracle was probably so each Jew would witness first hand that Hashem was God and the בעל was false. For if somebody who worshipped the בעל was just told about this by a friend it would not have the same effect on him (to the point where he'd drop his idols right then and there and praise Hashem as the one and only God) and he might even claim that "there was no miracle, that אליהו probably just secretly lit a match or performed some magic trick to burn his Korban, and בעל didn't answer the נביאי בעל because he was probably taking a nap" (see פרק יח פסוק כז).
In the future, at the time of the Moshiach we will again experience this great miracle where an area will be able to contain contents seemingly beyond its capacity. Then, Hashem will perform תחיית המתים on all of the Tzaddikim who have lived all the way back to the time of אדם הראשון and bring them to Eretz Yisrael. The land of Eretz Yisrael will then miraculously expand to hold many people and no one will suffer because of lack of space. May we all be זוכה to live to see the occurrence of this amazing miracle once again in the time of the Moshiach.