Why does ENO's salt effervesce on addition of water?

Hey friends, Sometimes you feel your stomach swallowed with gastric problems, then you surely drink ENO or the equivalent products after that you feel relaxed. 
Do you know how this ENO makes you relieved, there is one simple science behind it, ENO contains tartaric acid and sodium bicarbonate (these are a type of acid). When you add water in it, carbon dioxide is produced, when carbon dioxide is released into water, it causes effervescence appearing like bubble formation. Due to this effervescence, you feel belching and with this belch, your stomach gas releases easily from your body.