The reason? Probably a pacemaker left inside a body. The News & Star explains:
No-one was hurt in the incident and there was no disruption to funeral services or cremations.
The crematorium, in Dalston Road, is operated by the city council’s bereavement services department. A council spokesperson said: "There was a minor explosion within the crematorium’s cremator yesterday afternoon.
"The machinery continued to operate normally and there was no lasting damage.
"Staff members overseeing the machinery were unharmed and are investigating the possible cause.
"Cremations continued as planned and there were no disruptions to services."
It is understood that prior to cremations, it is the responsibility of the family and funeral director to ensure that nothing is within a coffin which may cause an explosion.
In this instance, it is believed the go-ahead for the cremation had been given by two doctors.
Pacemakers should be removed before cremation.