I really don't know how this strange behavior came out.
I had boost enabled, I disabled it as well as Drupal cache, no other cache module in place.
Drupal keeps caching nodes after update. I need to clear the cache after each edit to see the changes.

Where to look at?

Thanks for help


I assume that installing Boost requires editing the .htaccess file. Did you undo these changes?

Yes, I commented out the .htaccess boost section, though this is unnecessary.
I have 10 sites running on the same install, sharing the same .htaccess, not using boost - they have not problem


I found the problem.
This problem was only with content in panels. Panels cache was enabled hence my problem.
I guess that Panels cache is not that smart, it does not flush on update of its content.