"Population explosion" refers to a situation where the number of people in a specific area or the world grows very quickly, and there are more people than the resources available to support them. Full definition
In response to favourable conditions, they may undergo population explosions, called blooms. (environment.gov.au)
We have a massive population explosion right now and there are a lot of new churches popping up because of it. (redeeminggod.com)
Leaving a few annoying flies because you don't want to deal with them just leads to breeding and a future population explosion. (thefashionablehousewife.com)