Concatenation of max_times within 15 minute time intervals SQL

I am trying to write a sql query that pulls an ID and concatenates the max times within 15 minute time intervals starting from the first time.

i.e. for one log_id data might be

101 01:01 
101 01:08 
101 01:23 
101 02:01 
101 02:10 
101 02:16

we would want to display

101 01:01, 01:08, 01:23, 2:01, 2:16

any ideas?