The highest temperature at which water can exist in its liquid phase is 100 degrees Celsius (212 degrees Fahrenheit) at standard atmospheric pressure. At this point, water undergoes a phase change from a liquid to a gaseous state, known as boiling.
However, under specific conditions, water can exist in superheated states, where its temperature exceeds 100 degrees Celsius without boiling. Superheating can occur when water is heated in a clean container without any nucleation sites for bubble formation. This can result in the water reaching temperatures above its boiling point without actually boiling. Disturbing the superheated water, such as introducing an object or stirring it, can trigger a sudden and violent boiling process.
It's important to exercise caution when dealing with superheated water, as it can be unexpectedly volatile and cause burns or other hazards if not handled properly.
In extreme circumstances, such as in experimental settings, water can be heated to much higher temperatures under high-pressure conditions. For example, under high-pressure conditions found in certain industrial processes or scientific experiments, water can exist as a supercritical fluid, which means it is neither a liquid nor a gas and can reach temperatures well above 100 degrees Celsius. In these cases, water can reach temperatures of several hundred degrees Celsius or higher before transitioning to a different state of matter.