Personally, I would have my coolant checked for oil or gasoline contamination. A slightly faulty pressure relief system on your overflow tank could also lead to over-pressurization when running hot, followed by hose failure. A faulty head gasket, as was common on the straight 6s (I have suffered that failure on my c280) can lead to system overpressure even if the cap is capable of handling gradual overpressure. Again, hose stress is possible. A head gasket problem can lead to one of 3 problems, depending on your driving and the actual failure point.
You can have water into your oil return passages as the coolant pressurizes.
You can have oil into your coolant from a supply passage.
You can have the cylinder compression pressurize the coolant system if driven hard, or you can suck coolant into the cylinders under high vacuum conditions (the same ones that cause leaky valve seals to show themselves in a puff of oil smoke from the exhaust).
In any case, have your cap checked and your coolant analyzed. This will rule out 1 easy fix and 1 not-so-easy fix.