Creating sections each with title pages in beamers slides

This can be easily done using \AtBeginSection to place a frame with the section title (\insertsectionhead) inside a beamercolorbox:

\documentclass{beamer}
\usetheme{Madrid}

\AtBeginSection[]{
  \begin{frame}
  \vfill
  \centering
  \begin{beamercolorbox}[sep=8pt,center,shadow=true,rounded=true]{title}
    \usebeamerfont{title}\insertsectionhead\par%
  \end{beamercolorbox}
  \vfill
  \end{frame}
}

\title{The Title}
\author{The Author}
\institute{The Institute}

\begin{document}

\begin{frame}
\maketitle
\end{frame}

\section{Test section one}
\begin{frame}
test frame for section one
\end{frame}

\section{Test section two}
\begin{frame}
test frame for section two
\end{frame}

\end{document}

Probably, depending on the theme used (which was not mentioned in the question), you will need to adjust the settings for the box; in particular, you might need to deactivate the option shadow and/or rounded by setting them to false.