So what sense does the prefix при establish?
"Печь" is for "bake". Formally "припекать" is for moment of baking then crust/change in color/change in consistance appears. "При-" is like marker of some degree of completeness. Like in "вёл"->"привёл".
However in baking terminology form "запекать" is used usually.
"Припекать" is used usually as metaphor. "Солнце припекает" = "Sun has heated my skin to the level of strong/intense feelings (maybe pain).". In internet slang "припекло" can be used as analog of english "butthurt" in sense of "fried ass".