Additionally, this term is used in the field of demography when the subject of discussion is the tremendous upsurge in population of the twentieth century in the third world following an unnaturally fast mortality transition. The concept is that in a high mortality society, the introduction of basic health care and hygiene measures, especially for the very young, drives mortality down within one or two generations if introduction is quick and effective enough. That's not as good as it sounds, though, as humans in high mortality societies have a very high fertility rate in order to compensate for high mortality and thereby continue the species, and the fertility rate often lags behind the mortality rate when the mortality rate drops. It can take as long as thirty years for social customs to begin to adapt to new biological circumstances, and in this time the population will skyrocket or metaphorically "explode," hence the population bomb.

This term is not used often in serious articles on population and demography, but you'll be hard pressed to find a class on recent demography and demographic change that does not use that term in lecture and discussion regularly.