Short Notes:

At sea level, water heated to 100° Celsius begins to boil, which means that bubbles of water vapour form throughout th eliquid and rise to the surface. This happens because, at that temperature, the vapour pressure of the water slightly exceeds the atmospheric pressure. At higher altitudes, atmospheric is much lower and water boils at lower temperatures. Conversely, if the pressure on a liquid is increased, for instance, below sea level or in a pressure cooker, the boiling point is at a higher temperature.

Click here for a Flash presentation on why water boils faster than normal at high altitude.