Why Does Burping after Drinking Soda Burn the Nose?

I do not believe this question has actually been scientifically studied... but I can hazard a guess.

Sodas are those flavored fizzy drinks like Coca-Cola and Pepsi.

The "fizziness" is due to carbonation or carbon dioxide dissolved within the drink. When sodas are made, carbon dioxide is forced into the liquid under pressure so that there's more gas dissolved in the liquid than at regular air pressure. The bubbles you see and feel is caused by the carbon dioxide gas being released back into the air when exposed to back into regular air pressure (a closed can or bottle keeps the carbon dioxide under pressure within the liquid).

Such machines can even be purchased to make sodas at home (see below).

A soda becomes flat when all the carbon dioxide has been released back into the air.

In any case, why the burn?

Carbon dioxide (CO2) and water (H2O) together undergo a chemical reaction to form a very weak acid  called carbonic acid (H2CO3).

CO2 + H2O <--> H2CO3

So, after drinking some soda, the CO2 that is released reacts with the water inside your mouth, throat, and belly. The resulting carbonic acid, some of which is aerosolized, can than be burped up into the nose.

The nasal lining is quite sensitive, and when in contact with carbonic acid, can cause a burning sensation.

Now... does this actually happen?

Well, sounds like a potential neat research project that can potentially even be done by a high school student.