Troubleshooting occasional popping from solid state amp?

What I noticed is that the volume pot makes a pop when it's touched, could this mean the pot is the problem? Could be a grounding problem of the pot? Any advice on how to check it?

Yes. Could be a bad connection on the pot. Replace the pot - or, try contact cleaner spray if you're happy it's not a bad joint.

I noticed also the amp pops when the fridge turns on and off, any solution to this?

Identify which channel is involved. If it is both you have a power supply problem. I doubt a cold solder joint as that would have caused trouble a long time ago. I'd be more inclined to look at capacitors. You can replace them yourself by getting the value and rating then you can order the part from Digikey. Do not just heat up the joints and try to pull the cap out. Use a solder wick or sucker and remove all the solder then straighten the wire and gently remove the cap. You do not want to break the copper foil. 

Good luck,
Mike.

Op
I would spray liberally with a good electrical contact cleaner, all the pots the amp has, volume, balance, treble bass etc, whatever as dirt and dust gets built up behind these very easily.
As far as popping when the fridge turns on and off that is interference over the mains from the fridge compressor kicking on and off.
Can you place the amp on a totally different circuit to the fridge?
If not you would need to get some type of power conditioner/isolator for your audio circuit to prevent the pickup from the mains noise.
Good luck