Shifting gears up hill?

I had to make a right turn so I put the car in neutral made the turn but after I turned it was a small hill I went to put it into 2nd gear and about 50-100feet I notice the wouldn't accelerate in speed but the rpms went up alittle, the gas pedal was vibrating alot and I was hear a weird noise "it wasn't a grinding noise". I put it back in neutral and put it back into 2nd then it ran fine. Why happened, Why didn't go in gear what as then noise.