Antonyms for the word "boiling away" would include terms such as "cooling down", "freezing", "stabilizing", "settling", "calming", "chilling", "relaxing", "slowing down" or "cooling off." When an object or liquid is not boiling, it means it is at a lower temperature or in a state of equilibrium. Instead of boiling away, it can be said that it is simmering, heating, warming, or gently cooking. Antonyms for boiling away also convey a sense of peace or tranquillity, which may suggest a more passive or stable state rather than the intense activity or agitation of boiling.