  The metal rich globular cluster RZ 2109 in the massive Virgo elliptical
galaxy NGC 4472 (M49) harbours the ultra luminous X-ray source XMMU
122939.7+075333. Previous studies showed that this source varies between bright
and faint phases on timescales of just a few hours. Here, we report the
discovery of two peculiar X-ray bursting events that last for about 8 and 3.5
hours separated by about 3 days. Such a recurring X-ray burst-like behaviour
has never been observed before. We argue that type-I X-ray bursts or super
bursts as well as outburst scenarios requiring a young stellar object are
highly unlikely explanations for the observed light curve, leaving an aperiodic
disc wind scenario driven by hyper-Eddington accretion as a viable explanation
for this new type of X-ray flaring activities.
