Stacked boxes in beamer (or more generally LaTeX)

The following based on tcolorbox and tikz might serve as a point to start from:

documentclass{beamer}
usepackage{tcolorbox}
usepackage{tikz}
begin{document}
begin{frame}
frametitle{nested tcolorboxes}
begin{tcolorbox}[width=6cm] 
some contents in the larger surrounding box

  begin{tcolorbox}[hbox]
   smaller box
   end{tcolorbox}
end{tcolorbox}
end{frame}

begin{frame}
frametitle{overlapping tcolorboxes}
begin{tikzpicture}
  node (lowest) 
      {begin{tcolorbox}[width=4cm] 
       some contents in the lowest box
       end{tcolorbox}};
  node[anchor=north west] (middle) at (lowest.east) [xshift=-1cm]  
      {begin{tcolorbox}[width=3cm] 
       some contents in the middle box
       end{tcolorbox}};
  node (upper) at (middle.south west) [yshift=-0.1cm] 
      {begin{tcolorbox}[width=8cm] 
      some contents in the upper box
      end{tcolorbox}};
end{tikzpicture}
end{frame}
end{document}