cant say ive ever heard of that happening even with shocks that are completly boloxed, the wrong springs must be on the car, and there fore not doing there intended job of holding car up, so all weight is on the shock, the shock is compressed the whole way down and bottomed out hence the banging sound, you effectively have no shock absorbers, you should look around the shock towers and see is there any evidence of panel sealer cracking with the impact of no shock absorbtion
Also it may be that the wrong shocks are in the car and are 2 long, and shock is down to the full but still 2 long and holding car up and not letting springs take the weight, more likely springs do