Water can boil at room temperature if it is placed in a vacuum.

The boiling point of a liquid is not a fixed temperature but depends entirely on the surrounding atmospheric pressure. At standard sea level pressure of 101.3 kilopascals, water boils at 100 degrees Celsius. However, as pressure decreases, the energy required for molecules to break free from the liquid surface also drops significantly.When water is placed in a vacuum chamber and the air is evacuated, the external pressure eventually falls below the water's vapor pressure at room temperature. At approximately 3.17 kilopascals, water will begin to boil vigorously at 25 degrees Celsius. This phenomenon is a staple of physics demonstrations in institutions like the Massachusetts Institute of Technology to illustrate thermodynamic phase transitions.An amazing secondary effect occurs called evaporative cooling. As the fastest, most energetic molecules escape as gas, they take heat energy away from the remaining liquid. If the vacuum pump continues to remove the vapor, the temperature of the liquid water will plummet rapidly.Eventually, the water reaches its 'triple point' at 0.01 degrees Celsius and 0.61 kilopascals. At this precise state, the water exists as a gas, liquid, and solid simultaneously. If the pressure remains low, the water will eventually freeze into solid ice while it is still bubbling, demonstrating that boiling is a cooling process.