Flipping record causing series of loud pops

 Static electricity with the vinyl record and the cartridge as you flip it? I have owned tube phono stages for decades an have never had any pops. Does it seem controllable with flipping... or does it just happen if it sits there? I assume the table is grounded. 

You left the volume UP flipping records?

You say you swap, you have a switch or have to swap leads?

Make sure the ground and the leads are tight and plugged in all the way.

It's new? After it's warmed up tap the valves with a pencil. Make sure the volume is down. Up to two weeks to find out if transportation caused valve damage. It's just the cost of transporting valves via shipping..
Pull and reseat the valves..

If the timing of the "Pops" is random something is loose. Is something being shaken when the pops occur? Are you moving the tonearm?

Little more feedback about what you are doing..

Regards

The solution is what you are supposed to always be doing regardless- mute or change the input before doing anything with the turntable.