Display archive by month and then post-by-post?

I found a solution myself. Based on this thread: https://www.ads-software.com/support/topic/291728?replies=10.

Here is my solution:

<?php // Variables $month, $prevmonth, $year and $prevyear are used to section the archive display ?>
<?php 	$month = '';
		$prevmonth = '';
		$year = '';
		$prevyear = ''; ?>

<?php // Cycle through all the posts to display the archive ?>
<?php query_posts('showposts=-1'); ?>
<?php if (have_posts()) : while (have_posts()) : the_post(); ?>

	<?php // Find the month/year of the current post ?>
	<?php $year = mysql2date('Y', $post->post_date); ?>
	<?php $month = mysql2date('F', $post->post_date); ?>

	<?php // Compare the current month with the $prevmonth ?>
	<?php if ($month != $prevmonth) { ?>
		<?php // If it is different, display the new month and reset $prevmonth ?>
		<h4><?php echo $month . ' ' . $year; ?></h4>
		<?php $prevmonth = $month; ?>

	<?php // In case the previous post was a year ago in the same month ?>
	<?php } elseif ($year != $prevyear) { ?>
		<h4><?php echo $month . ' ' . $year; ?></h4>
		<?php $prevmonth = $month; ?>
		<?php $prevyear = $year; ?>
	<?php } ?>

	<?php // Display the post in this month ?>
	<p><a href="<?php the_permalink(); ?>"><?php echo mysql2date('d.m.y', $post->post_date); ?> - <?php the_title(); ?></a></p>

<?php endwhile; endif; ?>