Temporal implosion could occur when the time differential was shorted out between two points in an individual's time stream. If a person met their future self and made physical contact, the younger self would earth the older one to the present and they would be consumed by the time differential, hence temporal implosion. This could only happen to the older version of the person as the younger version still had to travel back in time to meet themselves.
Mariah Learman shook a Dalek's manipulator arm, causing the Dalek to temporally implode as it was a mutated version of Learman from the future. (AUDIO: The Time of the Daleks)
A TARDIS' DITO feature was described as a controlled temporal implosion. (PROSE: The Dimension Riders)