In Learners' Questions in Session 4, Dan looks at phrasal verbs with the word pop. Here's a guide to phrasal verbs. Multi-word verbs / Phrasal verbs type 1, 2, 3 & 4 ...

Here, the phrasal verb keeps on means continues. It has the same meaning as keeps but is slightly stronger. Other phrasal verbs that extend the meaning of the main verb are hurry up and sit down.