When driving on the highway today I heard a pop and then my van started shaking towards the rear end violently upon acceleration. It has not shook prior to today, but I did hear a pop the other day and thought I ran over something. I had also been hearing a rattling noise in the rear end. I drove it home from school today going an approx. speed of 35 mph and it steered, turned, and made it home. It was just shaking. Any ideas??

No pipe hanging, no flat tires, drive shaft and rear axle appear to be intact.