<em>The standard laboratory rule is to always add acids or bases to solvent and not the other way round.</em>
The dissolution of concentrated acids/bases in solvents (water) generates heat energy. Thus, if the solvent is added to them, a layer of hot weak acid or base will be formed and this will boil and spray around, causing an explosion.
On the other hand, if acid/base is added to solvents, they flow into the solvents and get diluted immediately without any boiling taking place. Hence, it is safe to add acid/base to solvents and not the other way round.
