The word "煮开" is formed by combining the character "煮", which means to boil and incorporates the fire radical "火" for meaning and "者" for sound, with the character "开", meaning to open or start. Here, "开" functions as a resultative complement attached to the verb "煮", indicating the outcome of the boiling action, specifically that the liquid reaches a boiling point. Together, they create a compound verb meaning to bring to a boil.