Are you sure it is popping from the nozzle and not clicking from the extruder motor? If it is clicking, see [Filament not extruding properly]. If it is indeed a popping nozzle, here are some pointers:
Dry filament
You’re trying to print moist filament. Some filaments attract and absorb moisture from the air at very high rates. When trying to print such filament, the moisture will turn into vapor and give small popping noises. Dry your filament before use, especially Nylon.
Retraction settings
Turn down your retraction settings. You’re HotEnd might be sucking in air, even though this is usually more of a whistle than a pop.