I see it as a result of a few things:
1) High VG juices have a higher boiling point, which means you will need more power than with a high PG juice.
2) Some tanks will lose internal pressure if not tightened properly. This causes the chamber to flood, which results in more juice hitting the coil than can be vaporized. If you are sucking hard enough (insert joke) then it will pull some of that juice into your mouth (vaping innuendos for days).
3) Subohm tanks require more power. If you're trying to vape them at 10 watts like we used to do with the old clearos, it isn't enough power to keep up with the liquid flow. Also, you need a big enough coil to handle the load (a tiny coil in a tank with big juice channels wont work).
4) If you don't have enough cotton between the coil, you will get the snap, crackle, pop (which sometimes will end up burning your mouth).
The goal should be to have enough liquid entering the chamber, but not so much that it floods or gurgles. If you feel juice entering your mouth (or if the vape feels really "wet"), then you probably have underwicked or need to up the wattage. Likewise, too little juice results in dry hits. There's a balance to be struck, and if you rebuild, it takes a bit of practice.
I've found temp control helps with a lot of these issues.