The "pop-less" microphone switch is generally a series R-C pair, where the R is, say, 1 MOhm, and the C a few µF. The switch shorts the R out; the R charges the capacitor to the bias level when unmuted, and so shorting the R produces very little pop. The capacitor then shorts the AC audio component.

XLR switches are easier, just short hot and cold, done. Works with all microphones and doesn't produce a pop, because XLR uses phantom power instead of T-power.