Running synchronous tasks on separate thread with FIFO

using System;
...

namespace mynamespace
{
    public class TaskQueue
    {
        private readonly ConcurrentQueue<Func<Task>> _tasks = new ConcurrentQueue<Func<Task>>();
        private readonly SemaphoreSlim _signal = new SemaphoreSlim(1);

        public void Enqueue(Func<Task> task)
        {
            _tasks.Enqueue(task);
            Task.Run(ProcessQueue);
        }

        public async Task EnqueueAsync(Func<Task> task)
        {
            _tasks.Enqueue(task);
            await ProcessQueue();
        }

        private async Task ProcessQueue()
        {
            await _signal.WaitAsync();
            try
            {
                if (_tasks.TryDequeue(out var task))
                {
                    await task();
                }
            }
            finally
            {
                _signal.Release();
            }
        }

        public int GetQueueCount()
        {
            return _tasks.Count;
        }

        public IEnumerable<Func<Task>> GetTasksInQueue()
        {
            return _tasks.ToArray();
        }

        public async Task WaitUntilEmpty()
        {
            int timeout = 300;//30 seconds
            while (_tasks.Count > 0 && timeout >= 0)
            {
                await Task.Delay(100);
                timeout--;
            }
            if(timeout == 0)
            {
                Debug.WriteLine("TaskQueue did not empty in 30 seconds");
            }
        }
    }
}