How kafka container stores its data between reloads?


I have running container johnnypark/kafka-zookeeper:1.1.1
doker inspect command shows that there are no volumes there:

“VolumeDriver”: “”,
“VolumesFrom”: null,
“Volumes”: null,

But despite this after reload I see earlier created topics with data in them. In another word, I see some data which was created by the previous container of that image.

Where it stores the data if there are no volumes?