In this experiment we are reducing Coca Cola and Coca Cola Zero until all of the water evaporates.
Coca Cola (Classic) contains about 10 grams of sugar per 100 grams of mass, while Coca Cola Zero, theoretically (and practically, as we will prove) contains 0% and therefore 0g of sugar.
Then why are Coca Cola Zero and Diet Coke sweet if they don't contain any sugar? Well, they contain artificial sweeteners such as aspartame and acesulfame potassium (aka acesulfame K, aka Ace K). Actually, they do contain the same amount of both sweeteners. As they don't contain any sugar, they are both very low on calories.
When water evaporated, original Coca Cola was smoking in bluish-grey color, meaning sugar was starting to burn. That's when we stopped boiling it and that is all caramelized sugar starting to burn.
As for Coca Cola Zero, all water evaporated leaving very small amount of residue, probably just colors and artificial sweeteners.
I hope this video was educational and interesting and made you rethink about your soft-drink consuming habits.