My experience exactly. As a Mechanical Engineer I am completely baffled by this, since the steam pressure inside the lower chamber is always extremely low (only slightly above ambient pressure outside the Moka pot), and there is no detectable leakage at the seal between the upper and lower...
I know this is an old thread, but I was happy to learn at least others had experienced this same problem and I'm not going crazy. My Bialetti Moka Express previously worked fine. Changed gasket only, and now only get spurts and splatters of coffee out the upper column while loud boiling sounds...