Evaporation and boiling are both terms applied to the change of a liquid to the vapour/gaseous state. This article argues that it is the formation of bubbles of vapour within the liquid that most clearly differentiates boiling from evaporation although only a minority of chemistry textbooks seems to mention bubble formation in this context. The importance of bubble formation is used to explore a much deeper, albeit a largely qualitative, explanatory basis of a number of interrelated phenomena. These include the fixed boiling point of liquids at a constant external pressure, the effect of pressure changes and of dissolved substances on boiling point, and nucleation, superheating and bump-boiling. (Contains 1 table, 2 boxes, 1 note, and 3 figures.)