If you have a bucket of lava and try and place it in another source block of lava that is already placed the breaking animation is shown and the sound for breaking a block is played.
MC-21350
Lava Glitch
Resolved
Duplicate
0
Daniel Black
(Unassigned)
Unconfirmed
Minecraft 1.6.1
Retrieved
This also happens with water but it is not the braking animation there are particles and the braking sound