Highcharts.chart('container', {

    xAxis: {
        categories: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
    },

    yAxis: {
        max: 300
    },

    series: [{
        data: [29.9, 71.5, 106.4, 129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, 95.6, 54.4]
    }]

}, function (chart) {

    var point = chart.series[0].data[8],
        text = chart.renderer.text(
            'Max',
            point.plotX + chart.plotLeft + 10,
            point.plotY + chart.plotTop - 10
        ).attr({
            zIndex: 5
        }).add(),
        box = text.getBBox();

    chart.renderer.rect(box.x - 5, box.y - 5, box.width + 10, box.height + 10, 5)
        .attr({
            fill: '#FFFFEF',
            stroke: 'gray',
            'stroke-width': 1,
            zIndex: 4
        })
        .add();
});