Hilchos Maasei Hakarbanos 2:10

Here’s what they did with the overflow of the libation vessels: if another offering was to be made, it was brought with that offering; if it remained overnight, it would be disqualified for use. If not, the overflow was sold and the money used to buy the “dessert” of the altar (i.e., additional communal offerings that were brought when the altar was otherwise idle).

Hilchos Maasei Hakarbanos 2:11

(Explaining the end of the previous halacha:) They would buy burnt offerings with the money from selling the overflow. These were completely burned (rather than eaten) and the hides were given to the kohanim.