After digging, I found the solution. In /resources/views/vendor/flash/message.blade.php, I had the following code which was working for Laravel 5.1

@if (Session::has('flash_notification.message'))
    @if (Session::has('flash_notification.overlay'))
        @include('flash::modal', ['modalClass' => 'flash-modal', 'title' => Session::get('flash_notification.title'), 'body' => Session::get('flash_notification.message')])
    @else
        <div class="alert alert-{{ Session::get('flash_notification.level') }}">
            <button type="button" class="close" data-dismiss="alert" aria-hidden="true">&times;</button>

            {{ Session::get('flash_notification.message') }}
        </div>
    @endif
@endif

But since there is been a change with Laracasts/flash view partial used to display messages, I put the new code in the file:

@foreach ((array) session('flash_notification') as $message)
    @if ($message['overlay'])
        @include('flash::modal', [
            'modalClass' => 'flash-modal',
            'title'      => $message['title'],
            'body'       => $message['message']
        ])
    @else
        <div class="alert
                    alert-{{ $message['level'] }}
                    {{ $message['important'] ? 'alert-important' : '' }}"
             role="alert"
                >
            @if ($message['important'])
                <button type="button"
                        class="close"
                        data-dismiss="alert"
                        aria-hidden="true"
                        >&times;</button>
            @endif

            {!! $message['message'] !!}
        </div>
    @endif
@endforeach

{{ session()->forget('flash_notification') }}

It's working perfectly now.