Based on Likutey Moharan lesson 24:

Likutey Halakhot, Orach Chaim, Nefilat Apayim #4 011-3

How the Jews in Egypt did not yet have the power of the settling and structuring of the mind to properly absorb and delve into the high level light of intellectual experience that Hashem shone into them at the Exodus, and that is why it was totally forbidden and dangerous to eat Chametz at the time as the fermentation and leaving status of that nourishment will cause them to ferment their minds at a time that they need to run out of Egypt etc.