Why isn't the render showing realtime progress? Sometimes when handling scenes from other users I get a render that doesn't show until it's completely done.

It's probably just a setting that's ticked on or off but I can't figure out where to find this or even what it's called nor what the purpose of this is.

Operating system: Windows 7 professional
Blender version: 2.78
Render engine: Cycles
Occurs both on CPU and GPU (msi GEFORCE GTX 980Ti)  rendering

Some in depth explanation on this matter would be greatly appreciated!
(advantages/disadvantages/...)

EDIT: (included a screenshot that shows the settings I'm using.)
Try to turn off "Save Buffers" in Properties -> Render -> Performance. It helped me in Blender v2.79