Or when water gets in your ear during the shower and when that water finally gets out. Same feeling

The Eustachian tube goes between the middle ear and back of the throat and is there to equalize the air pressure in your middle ear. When you yawn or swallow it opens. That's why yawning pops your ears when you're in an airplane. Often children's Eustachian tubes so not develope and they have chronic issues with fluid in the middle ear that can't drain, so they will have "tubes" installed in their eardrum which allows fluid to drain out of the middle ear into the ear canal.

I currently haven't been able to hear for 3 weeks because of trapped fluid due to some kind of sinus issue. The problem is that the snot gets thicker as it sits in there so it won't drain out. Hopefully it resolves on it's own, but I may have to have my eardrum sliced open and have it sucked out.

Wait

It shouldn't always pop ?
- Lots of people can pop their ears on demand by flexing the muscles that open the tube. Those muscles are the same ones that flex when yawning and sometimes when chewing.
  
  If your ears are always popping, I don't think that's necessarily bad, but maybe you're more susceptible to ear infections? If it's not painful and has always been like that it's probably fine, but mentioning it to your doctor next time you see them won't hurt.
You might be able to clear (or at least relieve) some of the pressure by doing a Eustachian Tube Massage

Apply pressure to the area below the ear and just behind the jaw bone, then follow the jawline down to the neck (I'm not sure if you go under the jaw or straight down the neck. I do both)

Obviously, if this causes pain, don't continue

(I am not a doctor)
- I've been trying all the tricks I can find including that one. Been breathing in steam from a bowl with a towel other my head, using a various forms of heat on my ears and face. Taking the good cold medicine that they keep behind the counter at the pharmacy plus Flonase, and antihistamines. Went through a week of antibiotics just in case. I started wearing a mask at work and outside in case it is allergies. I have one side that is getting unblocked finally, which was the first side to get blocked.
One thing I will say about tubes in the ear is that when done right, the procedure for getting them in is pretty painless. Had tubes throughout most of my early childhood, so I don't really remember them, but I did have to get a tube put in within the last 5 or so years. Worst part was the slight burning sensation of the stuff they put in to ensure it wouldn't hurt. Otherwise, no pain whatsoever.
- Did having the tube in affect your healing at all?