Here's my 2 cents.

I had the exact same thing happen to my 126 MB awhile back,
only in my case, it happened about a half mile from home.

The upper hose had hardened, thereby making it easy to slip off the plastic pipe. Many discussions have taken place here and elsewhere regarding why the plastic pipe breaks. If it were my car, I'd search for a new METAL-only replacement and hope the engine didn't over-heat enough to weaken/blow the head gasket.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"