I have a bizarre problem where my coolant violently bubbled & boiled over (leaking from underneath the car) when i shut the engine off - enough to empty the entire overflow container. As far as i can tell, no coolant lost while driving. And at no time did the temperature go above 215F - so no overheating?! Only driven the car once since, and no repeat of problem (and temp, as always, stays between 208-215)
I describe it more in the following topic (but unfortunately didn't pick an informative header, so the right expert may miss it.) sorry. hopefully it is okay to link to it here?
Bizarre symptoms (300C) - Help!