en.wikipedia.org/wiki/Illusion_of_explanatory_depth
In the experiment they conducted with 16 Yale undergraduate students, they asked them to rate their understanding of devices and simple items.
They were then asked to generate a detailed explanation of how they worked and then rerate their understanding of that item.
Consistently, ratings were lower after generating an explanation, suggesting they then began to understand that they lacked understanding of that item after attempting to explain.