1990 Toyota Corolla Too high pressure on the high pressure

Hi, when I wanted to park the car yesterday, in parking lot, I moved the driving wheel to maximum and instead of hitting the lock I felt like it is blocked at about half way. It was not a metallic block so I had the feeling that if I force it it will go. So I forced it, I applied more force on the driving wheel and I heard a spray-like sound and I realized that power steering oil was sprayed from the place where high power power steering hose connects to the ps reservoir. So I think that the pressure in the high pressure line was too big. What could be the problem? Is there a valve that sometimes releases the extra pressure to return line? Is the pump or the steering gear itself (part connected to the drive shaft)? Thank you.