A reason for them to pop loose: worn suspension components, especially the ball joints.

I wrote a DIY for E39 rear overhaul, you can see it below, E53 is very similar:

DIY: 1998 BMW 528i Complete REAR Suspension Overhaul - Bimmerfest - BMW Forums

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1998 E39 528i 5sp MT
2006 E53 X5 3.0 6sp MT