Geyser Causes Form and function
Most importantly, the temperatures near the bottom of the geyser become high enough to start boiling the water. Steam bubbles come out of the top of the column. They burst through the geyser's vent. Some water flows or splashes out. This makes the weight of the column of water and the pressure on the water below less. When this pressure is released, the hot water turns into steam. It boils violently.