This is why rubber duck debugging works. You start explaining to a rubber duckie what problem you have, how you're trying to solve it and what happens. Posting a question on a hostile forum or snarky IRC channel also works. When I think how to formulate my question best, to cause no misunderstanding, I often stumble upon the solution.

It is also why teaching people programming makes you a better programmer. Even if you're answering newbie questions, it often makes you re-evaluate your knowledge or realize you don't understand something as clearly as you thought. Even newbies have different needs and interests, so they ask different questions than you would.