Earlier quoted context omitted.
It's quite interesting that "boiling water" in many Slavic languages is actually a separate word (and not derived from "water", but from "boiling"; similar how the author mentions "ice" being used instead of "frozen water").
It was mentioned in other comments but boiled water is steam, and frozen water is ice. We do not have separate words for freezing water or boiling water. in the slavic languages do they have a different way to describe boiling or freezing milk, or any other liquid?
I don't know how it is in other languages but in English "boiled water" and "boiling water" refer to different things - boiled water may be steam or water that has underwent some boiling, e.g. for sanitation, on the other hand "boiling water" refers strictly to water that is in the process of boiling.
I can see why some languages may have a separate word for one of these concepts to avoid some of the ambiguity.
I'm not a fan of extending the language with new words unless they are compound (with or without spaces) but extending the dictionaries with more and better descriptions is a no-brainer, there's a lot missing from them.