Heat the liquid in a large, wide container rather than a high narrow one, or it can boil over.

液体加热时要放进宽大的容器里，不要放进细长的容器里，否则它会溢出来。

《柯林斯英汉双解大词典》

Bring to a boil. Simmer over low heat until liquid has reduced by half, about 2 hours.

开大火煮沸所有材料后，用慢火焖煮约2小时直到水份大约剩下一半。

youdao

Bring the liquid to a boil over medium-high heat and cook 1 to 2 minutes, until it reduces by half.

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