Steps: 

1. dig a hole in the ground.
2. put lava.
3. place a StructureBlock where the lava is.
4. destroy the StructureBlock.

#*results: "*Lava" is not there.

    5. put water.

    6. place a StructureBlock where the water is.

    7. destroy the StructureBlock.

Observed result: 

"Water" is still there.

Expected result: 

"Water" shouldn't be there.