The correct way of making a solution of acid in water is to:

The right way of making a solution of acid in water is by adding the acid into the water.
If we add water to the acid instead, it will be an exothermic reaction which will release a large amount of heat which may lead to an explosion. Therefore, the acid should be added to the water very slowly. For example:
                           ${C\left(g\right) +\mathit{ O}}_2 \to \mathit{ C}{O}_2\left(g\right) +\mathit{ Heat}$