I found that I cannot switch to the Lookdev/Rendered (Eevee) view with factory settings and the default cube without Blender 2.8 freezing (as of build 4b6fa4d897a 2018-08-12 05:22), but this older test scene I had saved several days ago works for some inexplicable reason.

After trying almost everything, in the end I found that if I resize the program window Blender doesn't freeze after switching to Lookdev/Eevee. It remains to be seen why the above scene works also with the maximized window, on the other hand.

EDIT: apparently, after Eevee has been used at least once with a reduced size window, Blender won't freeze afterwards after maximizing window size back and switching to/from the rendered view multiple times. (it still does if the viewport has a too large area)

I found that the issue does not occur with AMD Display drivers 18.7.1, but it does occur with 18.8.1. Curiously the OpenGL version reported in the driver was higher in 18.7.1 and from 18.6.1 to 18.7.1 there was change in version number.

It might be worth reporting this to the AMD driver team through more direct channels.