Thump sound while veering left and right.

[Flowers]

I drive a 2000 Subaru liberty heritage.
When I drive on the freeway/highway at about 110km p/hr (68 miles) and I veer left or right my car makes loud thump noise. It happens in the rear of the car.
What could it be, will it be expensive to get fixed?

[jacobraftery]

Is it like...

You're heading straight, Turn right, it bumps, return straight it bumps.
Like a noticeable, almost like a hammer on wood noise.

Have you had any accident damage to the car?
When my car started to make the same audible bump after I had some fairly major damage
to the front left. I took it back to the mechanic, he tightened the K fram bolts (which were all
replaced) and it solved the problem.

[GT_Tony]

deodorant/tyre shine can rolling around in your boot?

can you feel the knock? does it shake the car? could be a few things loose under your car