Sweating in humans demonstrates water’s tendency to absorb heat by overcoming the hydrogen bonds that hold its molecules together. This property makes it possible for humans to stay cool via sweating, because water requires immense levels of energy to evaporate.
Sweat on the skin's surface utilizes body heat to transition into a gaseous state as it evaporates, producing a cooling effect. Water (sweat) absorbs 580 calories/gram of energy at regular skin temperature to produce the cooling effect of perspiration evaporation. Sweating on the skin usually begins at 37 degrees Celsius or 100.4 degrees Fahrenheit. At boiling point, water uses 540 cal/gm to evaporate.