I am not a chemist, but I suspect that there is no such chemical.
Organic material (e.g. adventurers) is complex and composed of diverse molecules which contain diverse amounts of atoms which tend to be gases when liberated from those molecules.
It should be possible to concoct a compound or mixture which will violently react with some particular organic compound (e.g. cellulose), but do so in such a way that all reactants are solids or liquids at the average temperature of the reaction, resulting in only a little bit of gas bubbling out.
However, if the solvent compound is then introduced to a mixture of diverse organic compounds and water, it will react with whatever parts it reacts strongly with, leaving behind other elements, much of which will be gaseous at the reaction temperature, even if the reaction temperature is kept under the boiling point of water somehow. For a sufficiently strong acid this can even take place in pure water. Gases like to expand, which will violently eject uncontained reagents from the reaction (surface of the adventurer) and all over the floor of the lab (dungeon).
Consequently, any chemical sufficiently potent that the small amount that sticks to an adventurer could rapidly dissolve big holes through him will mostly froth away instead, leaving nasty chemical burns, but not big holes.