The plumbers came to fix it, and it never made the sound for them. They cleaned the elements and flushed the tank, and the noise is still gone, so I'm happy. I think there was something blocking the pressure valve, and it cleared itself when i cranked up the hot water in the shower this morning, because that's when it stopped. Figures. I didn't have to pay for it though, since we called the landlord-approved plumber.
The pilot on the furnace went out again yesterday too. I got Mom to come over and re-light it for me, 'cause I'm a chicken about gas. On the way over, I saw my car was leaking something. Since I had taken my car to the shop last week, the brakes had started getting soft. So I figured it was my brake fluid leaking out, which my mechanical Mommy confirmed. Bought some on the way back, but they were real bad by then, so I'm driving Michael's car tomorrow and dropping mine off at a different auto shop after work. I think the other shop broke my brake line on purpose so I'd go back to have it fixed. Ass monkeys.