With phenolphthalein (in 50% EtOH) as the indicator, and base as the titrant, it is common knowledge that the solution turns from colorless to magenta. However, with careful sub-drop addition, the solution actually first turns milky-white, then milky-pink, before it clears up to a transparent pink at the end point:
After learning about the existence of the “secret area”, many students did the titration with utmost care. It was fun (and pretty tense) to watch.
Chemistry-wise I am not too sure what is precipitating. (Both the acid / base forms of phenolphthalein should be completely soluble.) Surely I am not the first to notice the transition, but I have not seen this described in the literature. If you have any leads please do let me know.