The steam from the hot water quickly evaporated into the air.

evaporated 是动词 evaporate 的过去式。evaporate 由前缀 e-/ex-（表示"向外"）和 vapor（"蒸汽"）加上动词后缀 -ate 组成，字面意思是"变成蒸汽散发出去"，即"蒸发"。