I've been working with a band (tech, lights etc.) for five years or so and throughout that time I've seen their live show improve drastically. But their singer has the tendency to talk to much. He will do the usual introducing a song and then get caught up responding to the audience for five minutes. Other times he will spoil surprise musical numbers or planned cold starts by talking over things. (example being show intros, stage blackouts before a big dramatic start to a song). What would be a good way to approach this without offending?