I removed "Bookmarks Toolbar Items" (can be found in "View -> Toolbars -> Customize") from bookmarks toolbar. So it's empty now - no buttons, separators or any other toolbar objects. Before I removed the only item from the toolbar it was below adress toolbar and above tabs toolbar. Now it disappeared (it's checked though in "View->Toolbars").
I don't know how put the "Bookmarks Toolbar Items" back to the toolbar because it's empty and therefore hidden. I tried dragging the Bookmarks Toolbar Items into different spots between address bar and tabs toolbar, but it didn't work.