oil over
牛津高阶英汉双解词典
(of liquid in a pan, etc) boil and flow over the side of a pan, etc
（指锅等容器中的液体）沸腾而溢出:
The milk is boiling over. 牛奶沸腾得溢出来了.
朗文当代英语词典
if a liquid boils over when it is heated, it rises and flows over the side of the container.
eg:The milk was boiling over on the stove behind her.
美国传统词典
To overflow while boiling. 沸腾溢出
韦氏大学词典
to overflow while boiling or during boiling
Pot boils over,means that liquid in a pot overflows or flows over the side of the pot when it is heated to the boil.
壶烧开淌水了,意思是壶里的液体加热至沸腾时溢出来了或者漫过壶边流出来了.