[Tex/LaTex] How to force a column-break in a multi-column page

Question

I want to display my article's abstract and table of contents side-by-side, to save space. I'm using the multicol package, but it tries to keep each column the same height, and I can't figure out how to force it to move content into the second column.

Here's a mockup; I'm just padding out the abstract to show what it should look like. The layout is perfect, I just want a way to do this properly:

\usepackage{multicol}
\begin{document}
\maketitle

\begin{multicols}{2}
\section*{Abstract}

\lipsum[1-2]

a % padding to make the first column run to
  % end of page
a

a

a

a

a

a

a

a

a

a

a

a

\tableofcontents
\end{multicols}

And here's what it looks like, rendered (perfect except for the padding lines):

Answer 1

• Put \vfill\null after the last line to break.
• And then put \columnbreak after \vfill\null.

\documentclass{article}
\usepackage[a4paper,margin=2cm]{geometry}
\usepackage{lipsum,multicol}
\usepackage[colorlinks]{hyperref}
\title{Introduction to \LaTeX}
\author{xport}
\begin{document}

\begin{multicols}{2}
\maketitle
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section*{Abstract}
\lipsum[1-2]
\vfill\null
\columnbreak
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\tableofcontents
%\vfill\null
%\columnbreak
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Counter}
\lipsum[1]
\section{Box}
\lipsum[1]
\subsection{Parbox}
\lipsum[1]
\subsection{Rule}
\lipsum[1]
\end{multicols}
\end{document}