Scenario: a fairly well-used aerosol can, containing a high proportion of pressurised propellant versus product (in this case, lubricating oil, a small quantity of which has contaminated the base).
Location: upon a stool. Let's assume this stool has a conformable surface (eg not a granite or other impermeable material). So conceivably PVC or semi-soft paint.
Situation: this well-used spray-can has just been used, and shaken. It therefore possesses a metacentre of gravity which is generally-consistent with it's volume and shape.
However, over time (and as a function of ambient storage temperature) the oil product within the can begins to come out of co-colloidal suspension within the propellant, and coalesce internally towards the bottom of the can.
This initially means that the metacentre of gravity moves downwards, but (importantly) there is a constant episodic reduction in the quantity (cf mass) of oil, at a depletion rate which exceeds that of the propellant.
Ultimately, the quantity of residual propellant, in terms of lighter-than-air lift, is nearly equal to the mass of the remaining product plus the mass of the lightweight tin can (think: miniature tin balloon becomes almost empowered for takeoff). That can is now so ready to fall over...it wants to break free...of gravity...just by a fraction of a Newton. It has become lighter than it was, when originally placed upon the stool
Special catalytic circumstances 1: a tiny air draught, tips over the can. The meta-C-of-G instantly moves up the can, precessing the cylinder into a self-accelerating tumble. And there is a lubricated, warmed, convex air castor underneath this self-lifting can, semi-sealed upon a slippery stool, just perfectly-ready to facilitate an omni-axial tip-trip.
Special catalytic circumstances 2: older aerosol cans were sometimes filled with product and propellent via a plug-sealed feedhole in the centre of their convex bases. If this were to leak (again, assuming that a lot of their content has been expended) they would tend to become lighter, yet have a growing gas bubble of potential tip-lift underneath them, ready to assist in making the cans fall-over.
TL-DR a ghost blew it over