Because my memory seemed to be rapidly disappearing (according to the Task Manager graph), but I couldn't see any programs using it, I downloaded RAMMap to get a better picture of what's going on. Turns out all of my memory was being chewed up by AWE.
When I try to research this, however, everyone seems to say that AWE isn't enabled for SQL Server 2012 64 bit systems, since it isn't needed; the expanded memory that AWE would enable is directly accessible. But the system still will happily chew up memory in AWE until it reaches its limit.
How can I disable this and free the 24GB ram?