Bongs work on several basic principles of physics, all of which are very simple to understand. First one is the vacuum.
When you light up the bowl and weed starts getting lit, it releases smoke.
Once the weed is lit and you slowly start inhaling you create a quasi-vacuum which sucks in the smoke from the bowl and stores it in the chamber.
The bubbles that you see appearing once you start inhaling are actually the “lungs of the bong” as they create micro-vacuums that suck smoke into the chamber.
If you take your lips off the mouthpiece you will see that the smoke actually won’t leave the chamber in huge amounts. As it has cooled down going through the water it tends to stay inside the bong.
When you pull the slider or remove your finger from the carb, make sure to quickly inhale the remaining smoke from the chamber. Releasing the carb will make it so that you can easily swoop the smoke, as the pressure outside is larger than the pressure in the bong.
If you are a conservative smoker, getting a bong can be a great way to drop down your consumption even more. If you’d like to get high instantly, not spend a lot of your weed and not have to deal with rolling and such, then I strongly recommend you get yourself one of these.
It’s a stoner classic, really.