Gases dissolve too
Everything so far has dissolved a solid in a liquid. Do gases really dissolve in water as well? Two things you have seen say they do.
Opening a bottle
Bubbles of gas leave the liquid the instant a bottle of soda water or a soft drink is opened.
Heating a beaker
Bubbles of gas form on the walls of a beaker as water in it is heated — long before the water boils.
In both cases what left was gas that had been dissolved in the water. It could not have come out if it had not been in there.
How that much gas got in
In making soda, carbon dioxide is mixed with water mechanically under special conditions at high pressure. That is why a large amount of gas is dissolved in it — far more than water would hold on its own.
And how it gets into ordinary water
Water standing in nature is constantly in contact with the atmosphere. Small amounts of gases such as carbon dioxide and oxygen dissolve in it that way. It is not much, but the dissolved oxygen is what fish breathe.
Gases dissolve in liquids, and how much dissolves is not fixed — it depends on the conditions.