A psychological theory that explains why people remember only the outcome? I've read somewhere about a psychological theory that people often remember the end results or the outcome of a certain situation/discussion/conversation/etc, but not the details of it.

In other words, the theory postulates that people often forget about things like who invented the solution, or how this happened, or who should be doing this task. Rather, people tend to just remember what the solution was, what happened, and what task had to be done.

I don't remember exactly in what context I read about this theory. It could have been part of some other theory.

Does such a theory exist? If so, what is the name of that theory?
I'm not sure about the problem-solution context, but there is the fairly well-studied "peak-end" phenomenon in which people appear most sensitive to the strongest and/or the final levels of positive or negative experiences in an episode. Daniel Kahneman has done a lot of work on this phenomenon, you can find a list of his papers on his website. A fairly simple demonstration is in this article:

Kahneman, D., Fredrickson, D.L., Schreiber , C.A. , &amp; Redelemeier, D.A. (1993). When more pain is preferred to less: Adding a better end. Psychological Science, 4(6), 401-405.