The closest thing I can think of is what is sometimes called an "epistemically transformative experience". In Frank Jackson's "Knowledge Argument" against physicalism Mary is sometimes described as having an "epistemically transformative experience" when she leaves her room and experiences redness for the first time--- even though she knew all of the physical facts about redness.
Recently, Laurie Paul has written a paper on how having a child is a similarly "epistemically transformative experience" called "What Mary Can't Expect When She's Expecting". This call for papers from Res Philosophica gives a brief description of the topic. From the CFP:
When Mary sees color for the first time, her experience is transformed in a way that she could not have predicted: she could not know what it would be like for her to see red for the first time. Such experiences are transformative for an agent in the sense that they are radically unlike the agent’s previous experiences with regard to their phenomenal character, intensity, and overall cognitive significance.
I could see your "eureka moments" as a sort of epistemically transformative experience. Despite knowing all sorts of facts, these facts don't have as much cognitive significance as they do after things "click". Just like although Mary knows a whole lot about the color red, these facts don't mean much until she experiences "what it's like" to see red.
I'm not sure how much has been written on the subject of epistemically transformative experiences. Following that CFP from Res Philosophica might be worthwhile if this is the phenomenon you're interested in.
It just occurred to me that there is a research trend in epistemology and theories of epistemic value that distinguishes "knowledge" from "understanding". I don't know much about the area, but you can find some discussion of the topic in this SEP article. I take it that whether there even is a significant such distinction is controversial.