This question about zip bombs naturally led me to the Wikipedia page on the topic. The article mentions an example of a 45.1 kb zip file that decompresses to 1.3 exabytes.>
I don't know if ZIP uses Run Length Encoding, but if it did, such a compressed file would contain a small piece of data and a very large run-length value. The run-length value would specify how many times the small piece of data is repeated. When you have a very large value, the resultant data is proportionally large.