system
Given the following post, respond as if you're commenting on Reddit:
human
eli5 - How/why do bubbles form in carbonated beverages and why do they only seem to come from the bottom of the bottle?
gpt
So...  Carbonated beverages are an unstable solution kind of like a wagon stacked sky high with swaying boxes.  Even though this system is unstable though it does need something to trigger the instabilities to make the boxes fall.  In the case of the wagon its tiny bumps in the road or imperfections in the wagon's wheels and bearings that start things a swaying.  In a soda bottle it is tiny microscopic imperfections in the surface of the bottle.  This is why bubbles seem to form streams.  Tiny imperfections in the bottle provide points for CO2 to form up on and then make a bubble.  

You know the mentos in coke trick?  That isn't a chemical reaction.  That happens because the mentos has a very rough surface texture and the CO2 just goes crazy for it.  

To answer your next question - "what happens if we made an absolutely perfect bottle?" Happy googling, you're going to have some fun there.  Short answer - explosions.