The chemical equation is as follows:
CaCO3(s)+2HCl(aq)--->CO2(g)+H2O(l)+CaCl2(aq)
The general formula for an acid reacting with a carbonate is:
Carbonate+Acid--->Carbon dioxide+Water+Salt
These general equations should be learnt by heart to make exams easier.
Due to the formation of carbon dioxide, there would be effervescence. The solid will start to disappear as it is reacting to form an aqueous salt. If the acid is highly concentrated, the reaction would be more vigorous as there would be more HCl molecules to react with the CaCO3. This is also an example of a neutralisation reaction, as calcium carbonate is a base.