Summer is the time for chocolate bloom, even inadvertent. We found this Trader Joe's 72% cacao dark chocolate bar melted in a hot car.
After it sat on the counter for a few weeks, it had bloomed so much that traces of pure cocoa butter lined the edges. I scraped some off and rubbed it in my fingers before I tasted it--pure cocoa butter without any chocolate taste at all, and maybe even without any sugar (it's hard to tell from a 1-mm shaving).
In this photo, you can see the white cocoa butter at the corners of the chocolate bar.
The rest of the bar crumbled when broken, instead of snapping cleanly like well-tempered chocolate.