Cauldron explosion

Neville's potion has, once again, blown up in his face. i think by this point the poor teen is excepting the fact that he will A)always suck at potions and B)fail his NEWTS in potions class. Of course, harry isn't much better off, by this point their potions should be setting off a lavender vapor, however the boys' potions are setting off acid green and blue vapors.