Ez bar curls + weird feeling in arm

Whats up yall, ive been getting stronger so ive been putting more on the bar for my curls. Currently do ezbar + 25's for 8-10 reps for 5 sets.

But when I do, around rep 5 and on per set, my arm starts to feel like the muscles vibrating. I feel it from mid bicep down to my wrist? Whats up with that? Is it a sign its about to tear? Theres no pain, just feels like intense vibration of the muscles cuz my arms dont shake.

Make sense??

Any advice. Thanks.