boil away

So he shut his lips firmly and let the squire and the colonel boil away as best they might between themselves.

If all the water were allowed to boil away, a layer of mud or of other impurities would be found at the bottom of the vessel.

Now add sufficient water to enable you to boil them, and let the water boil away till very little is left.

Truth, law, and language fairly boil away from them at the least touch of novel fact.

Add more water should it boil away or the soup get too thick.