Popping is caused by wind hitting the microphone. Beatboxers suffer from this although on some mics they can turn it to their advantage using the wind noise to add bass to kick drums. To minimise wind noise, you can use a pop shield. This is a mesh suspended infront of the mic such as a pair of tights (pantyhose) stretched over a coathanger or a splashguard from a deep fat fryer. Of course you can go out and spend money on a professional pop shield!