Listen. I know hot water, mainly because I am always in it. A new study reports the hottest water ever recorded 464 degrees C (867.2 F). That so hot the water is in the vapor-phase supercritical region (say three time out loud), basically somewhere between gas and liquid. But doesn’t water boil, i.e. go into the gas phase, at 99.97 degrees C? It does at 1 atm but at 3000 meters the increased pressure allows water to stay a liquid at higher temperatures.