I have read accounts of both Xenopus (ACF) and Hymenochirus (ADF) leaving the water, especially at night, to feed. Although, under normal circumstances, there is no need for pipids to leave the water. When their home pond dries up, Xenopus will often migrate long distances over land. It is clear that this behavior represents a considerable advantage for the colonization of new habitats. Pipids are indeed tough animals and can survive extreme conditions.

In a captive environment, the frog is probably searching for a midnight snack I also understand that some pipids, especially Sillurana, like to rest on plastic lily pads and bask. Make sure you provide some hiding places for your ADF.