I talked about the cool taste with some of the guys (including women) from the physics circus here at UCSB, and we're guessing you're on the right track with that one - but it might be the other phase change: menthol is a cooling ingredient, and it probably cools by evaporation? ... Do you have a Merck Index? My Merck Index says menthol boils at 212 deg. C, but it melts at 41-43 deg. C, which is near body temperature, so your theory may be the correct one.